Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/30—Controlling fuel injection
  • F02D41/38—Controlling fuel injection of the high pressure type
  • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
  • F02D41/402—Multiple injections
  • F02D41/403—Multiple injections with pilot injections
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/30—Controlling fuel injection
  • F02D41/38—Controlling fuel injection of the high pressure type
  • F02D41/3809—Common rail control systems
  • F02D41/3836—Controlling the fuel pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/06—Fuel or fuel supply system parameters
  • F02D2200/0602—Fuel pressure
  • F02D2200/0604—Estimation of fuel pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2250/00—Engine control related to specific problems or objectives
  • F02D2250/04—Fuel pressure pulsation in common rails
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/40—Engine management systems

Definitions

• the present invention relates to a fuel injection system of an internal combustion engine.
• An internal combustion engine designed so that the nozzle chambers of fuel injectors are connected to a common rail through high pressure lines and performing two fuel injections, for example a pilot injection and a succeeding main injection, is known (for example, see Japanese Unexamined Patent Publication (Kokai) No. 2000- 18074).
• Kanai Japanese Unexamined Patent Publication
• the pressure wave generated in a nozzle chamber of a fuel injector at that time propagates through the high pressure line and reaches the common rail.
• An object of the present invention is to provide a fuel injection system of an internal combustion engine able to accurately control the injection amount to the target value even when using a common rail.
• a fuel injection system of an internal combustion engine provided with a common rail and fuel injectors connected to the common rail, performing fuel injection from each fuel injector at least the two times of prior injection and later injection during one cycle of the engine, and changing in fluctuation amount of the later injection with respect to a target value depending on a time interval from when the prior injection is performed to when the later injection is performed
• the fuel injection system of an internal combustion engine provided with a storage device for storing a reference fluctuation amount of the later injection changing along with a reference fluctuation pattern along with an increase in the time interval when the rail pressure is a predetermined reference rail pressure and storing a contraction rate or expansion rate of the fluctuation pattern when contracting or expanding the fluctuation pattern of the fluctuation amount of the later injection when the rail pressure is not the reference rail pressure to overlay it on the reference fluctuation pattern
• a calculation device for using the contraction rate or expansion rate to calculate the fluctuation amount of the later injection in accordance with the rail pressure from the reference fluctuation amount and time interval
• FIG. 1 is an overview of a compression ignition type internal combustion engine
• FIG. 2 is a side sectional view of a tip of a fuel injector
• FIGS. 3A and 3B are views of injection patterns
• FIGS. 4A and 4B are views of maps of injection amounts
• FIGS. 5A and 5B are views of maps of main injection timing etc.
• FIGS. 6A to 6C are views of fluctuation amounts of main injection
• FIGS. 7A to 7C are views of fluctuation amounts of main injection
• FIGS. 8A and 8B are views of fluctuation amounts of main injection
• FIG. 9 is a flow chart of fuel injection control
• FIGS. 10A to 10D are views of contraction rates or expansion rates
• FIGS. 11A to 11C are views of fluctuation amounts of valve opening timing of a needle valve
• FIGS. 12A and 12B are views of fluctuation amounts of main injection
• FIGS. 13 and 14 are flow charts of fuel injection control
• FIGS. 15A to 15C are views of contraction rates or expansion rates
• FIGS. 16A to 16D are views of contraction rates or expansion rates
• FIGS. 17 and 18 are flow charts of fuel injection control.
• BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIG. 1, 1 is a compression ignition type internal combustion engine body, 2 a combustion chamber of a cylinder, 3 a fuel injector for injecting fuel into a combustion chamber 2, 4 an intake manifold, and 5 an exhaust manifold.
• the intake manifold 4 is connected through an intake duct 6 to an outlet of a compressor 7a of an exhaust turbocharger 7.
• the inlet of the compressor 7a is connected to an air cleaner 8.
• the intake duct 6 has arranged inside it a throttle valve 9 driven by a step motor.
• the exhaust manifold 5 is connected to an inlet of an exhaust turbine 7b of the exhaust turbocharger 7.
• the exhaust manifold 5 and the intake manifold 4 are connected to each other through an exhaust gas recirculation (hereinafter referred to as an "EGR") passage 10.
• the EGR passage 10 has an electronic control type EGR control valve 11 arranged in it.
• each fuel injector 3 is connected through a fuel feed line 12 to a common rail 13.
• the common rail 13 is supplied inside it with fuel from a fuel tank 15 by an electronic control type variable discharge fuel pump 14.
• the fuel supplied to the common rail 13 is supplied through the fuel feed lines 12 to the fuel injectors 3.
• the common rail 13 is provided with a fuel pressure sensor 16 for detecting the fuel pressure in the common rail 13. Based on the output signal of the fuel pressure sensor 16, the discharge of the fuel pump 14 is controlled so that the fuel pressure in the common rail 16 becomes the target fuel pressure.
• An electronic control unit 20 is comprised of a digital computer and is provided with a ROM (read only memory) 22, RAM (random access memory) 23, CPU (microprocessor) 24, input port 25, and output port 26 all connected by a bidirectional bus 21.
• FIG. 2 is an enlarged view of a fuel injector 3. As shown in FIG.
• the fuel injector 3 is provided with a needle valve 31 able to sit on a valve seat 30, a suck chamber 32 formed around a tip of the needle valve 31, an injection port 33 extending from the suck chamber 32 to the inside of the combustion chamber 2, and a nozzle chamber 34 formed around the needle valve 31.
• the nozzle chamber 34 is connected to the common rail 13 through a high pressure fuel feed passage extending through the inside of the body of the fuel injector 3 and the inside of the fuel feed line 12, that is, the "high pressure line 35".
• the high pressure fuel in the common rail 13 is supplied through the high pressure line 35 to the inside of the nozzle chamber 34.
• the fuel injector is formed inside it with a pressure control chamber 36 facing the back surface of the needle valve 31.
• the pressure control chamber 36 is provided inside it with a compression spring 37 pressing the needle valve 31 toward the valve seat 30.
• the pressure control chamber 36 is connected on the one hand through an inlet side constriction 38 to the middle of the high pressure line 35 and on the other hand through an outlet side constriction 39 to a fuel overflow port 41 controlled to open and close by an overflow control valve 40.
• the pressure control chamber 36 is continuously supplied with high pressure fuel through the constriction 38. Therefore, the pressure control valve 36 is filled with fuel.
• the fuel overflow port 41 is closed by the overflow control valve 40, as shown in FIG. 2, the needle valve 31 sits on the valve seat 30. Therefore, the fuel injection is stopped. At this time, the nozzle chamber 34 and the pressure control chamber 36 become the same fuel pressure.
• the overflow control valve 40 opens, that is, it opens the fuel overflow port 41, the high pressure fuel in the pressure control chamber 36 flows out through a constriction 39 from the fuel overflow port 41 and therefore the pressure in the pressure control chamber 36 gradually flows.
• the needle valve 31 rises and the injection of the fuel from the injection port 33 is started. That is, the pressure control chamber 36 and the fuel overflow port 41 are provided between them with a constriction 39. Further, due to other delay elements, the injection of fuel is started a little while after the overflow control valve 40 opens.
• FIGS. 3A and 3B show two representative fuel injection methods.
• FIG. 3A shows the case of performing a pilot injection P before a main injection M.
• the pilot injection P is the prior injection and the main injection M is the later injection.
• FIG. 3A shows the case of performing a pilot injection P before a main injection M.
• the pilot injection P is the prior injection and the main injection M is the later injection.
• 3B shows the case of performing a plurality of pilot injections P l P 2 before the main injection M and performing a plurality of post injections P 3 , P 4 after the main injection M.
• the pilot injection P 2 the later injection
• the pilot injection ⁇ 1 becomes the prior injection.
• the pilot injections P lf P 2 become the prior injections.
• the pilot injections P lf P 2 and the main injection M become the prior injections. Note that the present invention will be explained taking as an example the case of performing the pilot injection P before the main injection M as shown in FIG. 3A.
• the target total injection amount QT is stored in advance in the ROM 22 in the form of a map as a function of the depression of the accelerator pedal 17, that is, the accelerator opening degree L, and the engine speed N as shown in FIG. 4A.
• the target main injection amount QM is stored in advance in the ROM 22 in the form of a map as a function of the total injection amount QT and the engine speed N as shown in FIG. 4B.
• the target pilot injection amount QP is obtained by subtracting from the total injection amount QT the main injection amount QM.
• the injection start timing ⁇ M of the main injection M is stored in advance in the ROM 22 in the form of a map as a function of the total injection amount QT and the engine speed N as shown in FIG. 5A. Further, the time interval from when the prior injection is performed to when the later injection is performed is set in advance. In this embodiment of the present invention, the time interval TI from when the pilot injection P is started to when the main injection M is started is stored in advance in the ROM 22 in the form of a map as a function of the total injection amount QT and the engine speed N as shown in FIG. 5B. The injection start timing ⁇ P of the pilot injection P is calculated from the injection start timing ⁇ M of the main injection M and the time interval TI .
• the target rail pressure in the common rail 13 is set in advance. This target rail pressure generally speaking becomes higher the greater the total injection amount QT.
• the pressure in the nozzle chamber 34 rapidly drops. If the pressure in the nozzle chamber 34 rapidly drops in this way, a pressure wave is produced. This pressure wave propagates through the inside of the high pressure line 35 toward the common rail 13. Next, this pressure wave is reflected at the open end of the high pressure line 35 leading toward the inside of the common rail 13.
• this pressure wave proceeds through the high pressure line 35 toward the nozzle chamber 34 in the state with the pressure inverted with respect to the mean pressure, that is, in the form of a high pressure wave, and causes the nozzle chamber 34 to become high in pressure temporarily.
• the inside of the nozzle chamber 34 becomes temporarily a high pressure due to the reflected wave in the common rail 13.
• the needle valve 31 closes, the flow of the fuel is rapidly blocked, so the pressure inside the nozzle chamber 34 temporarily rises and a pressure wave is formed.
• This pressure wave also propagates through the inside of the high pressure line 35, is reflected at the common rail 13, and returns to the inside of the nozzle chamber 34.
• the opening and closing operation of the overflow control valve 40 also causes generation of a pressure wave propagated through the inside of the nozzle chamber 34. That is, if the overflow control valve 40 opens, the pressure at the fuel overflow port 41 rapidly falls, so a pressure wave is generated. If the overflow control valve 40 closes, the pressure of the fuel overflow port 41 rapidly rises, so a pressure wave is generated. These pressure waves pass through the pair of constrictions 39, 38 to be propagated through the nozzle chamber 34 and cause the pressure in the nozzle chamber 34 to rise or fall. Simultaneously, the pressure waves are reflected in the nozzle chamber 34 and are propagated toward the common rail 13 or the fuel overflow port 41.
• the abscissa Ti shows the time interval (msec) from when the pilot injection P was started to when the main injection M is started, while the ordinate dQ shows the fluctuation amount (mm 3 ) of the injection amount of the main injection M with respect to the target value.
• the D marks show when the rail pressure is 48 MPa
• the o marks show when the rail pressure is 80 MPa
• the ⁇ marks show when the rail pressure is 128 MPa. Note that FIGS. 6A to FIG. 6C show when the main injection amount is small, while FIGS.
• FIGS. 6A to 6C show when the pilot injection amount is 2 (mm 3 ) and the main injection amount is 2 (mm 3 ), while FIGS. 7A to 7C show when the pilot injection amount is 2 (mm 3 ) and the main injection amount is 20 (mm 3 ) .
• FIG. 6A and FIG. 7A show the actual fluctuation amount dQ of the injection amount of the main injection M with respect to the target value for three different rail pressures. As explained above, if the fuel pressure in the nozzle chamber 34 becomes higher, the main injection amount increases, while if the fuel pressure in the nozzle chamber 34 becomes lower, the main injection amount decreases, so it is learned from FIG. 6A and FIG.
• the fuel pressure in the nozzle chamber 34 repeatedly rises and falls, that is, pulsates.
• the fluctuation patterns of the main injection amounts expressed by the curves differ in period, that is, the higher the rail pressure, the shorter the period, but rise and fall by similar forms.
• the fuel pressure in the nozzle chamber 34 fluctuates due to the pressure wave propagated between the nozzle chamber 34 and common rail 13 or between the nozzle chamber 34 and the fuel overflow port 41.
• the distance between the nozzle chamber 34 and the common rail 13 is a fixed length and the distance between the nozzle chamber 34 and fuel overflow port 41 is also a fixed length, so if the propagation speed of the pressure wave is constant, the fuel pressure generated in the nozzle chamber 34 after the pilot injection P is performed will pulsate by a set fluctuation pattern.
• the propagation speed of a pressure wave changes depending on the fuel pressure and fuel temperature. That is, the propagation speed of the pressure wave is expressed by the square root of (E/ ⁇ ) «g where E is the volume elasticity, ⁇ is the density of the fuel, and g is the acceleration of gravity. That is, the propagation speed of the pressure wave is proportional to the square root of the volume elasticity E.
• the volume elasticity E is proportional to the fuel pressure and inversely proportional to the fuel temperature. Therefore, the propagation speed of the pressure wave becomes faster the higher the fuel pressure and becomes slower the higher the fuel temperature. That is, the propagation speed of the pressure wave becomes faster the higher the rail pressure. Therefore, when the rail pressure becomes higher, the period of fluctuation of the fuel pressure in the nozzle chamber 34 becomes shorter. At this time, the fuel pressure in the nozzle chamber 34 fluctuates in a form with the fluctuation pattern contracted in the abscissa direction in FIG. 6A and FIG. 7A, that is, in the time interval axis direction. Therefore, as shown in FIG. 6A and FIG.
• FIG. 6B and FIG. 7B show the case when making the fluctuation pattern contract when the rail pressure is 48 MPa and making the fluctuation pattern expand when the rail pressure is 128 MPa so that the period of upward and downward fluctuation of the fluctuation pattern matches the period of upward and downward fluctuation of the reference fluctuation pattern in this way.
• each fluctuation pattern When it is possible to standardize each fluctuation pattern to a common fluctuation pattern in this way, it is possible to modify the time interval by the contraction rate or expansion rate of each fluctuation pattern and use the modified time interval to find the fluctuation amount dQ of the main injection at each rail pressure from the common reference fluctuation pattern. For example, if making the fluctuation pattern of the fluctuation amount dQ of the main injection when the rail pressure is 80 MPa in FIG. 7A the common reference fluctuation pattern, the fluctuation amount dQ of the main injection at each time interval Ti when the rail pressure is 48 MPa matches with the reference fluctuation amount dQ of the main injection at the reference fluctuation pattern when contracting the time interval Ti by the contraction rate of the fluctuation pattern at the time of 48 MPa.
• the contraction rate or expansion rate of the fluctuation pattern at each rail pressure is multiplied with the time interval Ti to obtain the modified time interval.
• the reference fluctuation amount dQ at the reference fluctuation pattern in accordance with that modified time interval matches with the fluctuation amount dQ of the main injection at each rail pressure. If using the modified time interval in this way, if storing only the reference fluctuation amount dQ of the main injection at the reference fluctuation pattern, it is possible to find the fluctuation amount dQ of the main injection at each rail pressure from this reference fluctuation amount dQ. That is, in the present invention, the reference fluctuation amount of the later injection, changing along with the reference fluctuation pattern along with an increase in the time interval Ti when the rail pressure is a predetermined reference rail pressure, is stored in advance.
• the contraction rate or expansion rate of the fluctuation pattern when contracting or expanding the . fluctuation pattern of the fluctuation amount of the later injection to overlay it on the reference fluctuation pattern when the rail pressure is not the reference rail pressure is stored in advance.
• the fluctuation amount of the later injection in accordance with the rail pressure is calculated from the reference fluctuation amount and time interval Ti.
• the reference fluctuation amount dQ of the later injection at the reference rail pressure is stored in advance as a function of the time interval Ti.
• the contraction rate or expansion rate of each fluctuation pattern when overlaying the fluctuation pattern at a representative rail pressure on the reference fluctuation pattern is stored in advance.
• the modified time interval is found.
• the reference fluctuation amount dQ of the later injection in accordance with this modified time interval is made the fluctuation amount of the later injection at the current rail pressure.
• FIG. 6B and FIG. 7B the fluctuation amount dQ of the main injection at the same time interval Ti becomes greater the higher the rail pressure. Therefore, to standardize the fluctuation pattern at each rail pressure to the common reference fluctuation pattern, it is preferable to contract or expand the fluctuation pattern at each rail pressure in accordance with the rail pressure in the ordinate direction of FIG. 6B and FIG.
• FIG. 7B that is, in the direction increasing or decreasing the fluctuation amount dQ of the main injection.
• FIG. 6C and FIG. 7C show the case of contracting or expanding the fluctuation pattern at each rail pressure in the direction increasing or decreasing the fluctuation amount dQ of the main injection to overlay it on the reference fluctuation pattern.
• the contraction rate or expansion rate of the fluctuation pattern when contracting or expanding the fluctuation pattern of the fluctuation amount of the later injection to overlay it on the reference fluctuation pattern is stored for each rail pressure.
• the contraction rate or expansion rate of the fluctuation pattern at each rail pressure is comprised of a first contraction rate or first expansion rate in a direction increasing or decreasing the time interval Ti and a second contraction rate or second expansion rate in a direction increasing or decreasing the fluctuation amount dQ of the injection amount.
• These second contraction rate and second expansion rate are functions of the rail pressure.
• FIG. 8A shows the fluctuation amount dQ of the main injection when making the injection amount of the main injection 5 (mm 3 ), 10 (mm 3 ), 20 (mm 3 ), 30 (mm 3 ), and 40 (mm 3 ) in the state maintaining the rail pressure at 48 MPa.
• the contraction rate or expansion rate of the fluctuation pattern when contracting or expanding the fluctuation pattern of the fluctuation amount of the later injection to overlay it on the reference fluctuation pattern is stored for each injection amount of the main injection.
• the fluctuation amount dQ of the main injection is calculated.
• the contraction rate or expansion rate of the fluctuation pattern at each rail pressure is comprised of a first contraction rate or first expansion rate in a direction increasing or decreasing the time interval Ti and a second contraction rate or second expansion rate in a direction increasing or decreasing the fluctuation amount dQ of the injection amount.
• These second contraction rate and second expansion rate are functions of the injection amount of the main injection.
• the contraction rate or expansion rate of the fluctuation pattern at each rail pressure is comprised of a first contraction rate or first expansion rate in a direction increasing or decreasing the time interval Ti and a second contraction rate or second expansion rate in a direction increasing or decreasing the fluctuation amount dQ of the injection amount.
• the time interval is multiplied with the first contraction rate or first expansion rate to find the modified time interval, the reference fluctuation amount dQ in accordance with this modified time interval Ti is multiplied with the reciprocal of the second contraction rate or the reciprocal of the second expansion rate, and the obtained amount is made the fluctuation amount of the later injection.
• the fuel injection control for controlling the fuel injection to a target value will be explained with reference to the fuel injection control routine shown in FIG. 9. Referring to FIG. 9, first, at step 100, the total injection amount QT is calculated from the map shown in FIG. 4A. Next, at step 101, the main injection amount QM is calculated from the map shown in FIG. 4B.
• the total injection amount QT is subtracted by the main injection amount QM to calculate the pilot injection amount QP.
• the main injection start timing ⁇ M is calculated from the map shown in FIG. 5A.
• the time interval TI is calculated from the map shown in FIG. 5B.
• the pilot injection start timing ⁇ P is calculated from the main injection start timing ⁇ M and the time interval TI.
• the contraction rate or expansion rate Kl when contracting or expanding the fluctuation pattern of the fluctuation amount dQ of the main injection amount in a direction increasing or reducing the time interval in accordance with the rail pressure based on the rail pressure detected by the fuel pressure sensor 16 or the mean value of the rail pressure in a fixed time (hereinafter referred to simply as the "rail pressure") to overlay it on the reference fluctuation pattern is calculated.
• This contraction rate or expansion rate Kl is shown in FIG. 10A. If the reference rail pressure is 80 MPa, when the rail pressure is near 80 MPa, the contraction rate or expansion rate Kl is 1.0.
• the contraction rate or expansion rate Kl of the fluctuation pattern is multiplied with the time interval TI so as to calculate the modified time interval Ti.
• the reference rail pressure is made 80 MPa
• the reference main injection amount QM is made 20 (mm 3 )
• the reference pilot injection amount QP is made 2 (mm 3 )
• the reference fluctuation amount dQ is calculated.
• the contraction rate or expansion rate K2 of the fluctuation pattern when contracting or expanding the fluctuation pattern of the main injection amount in a direction increasing or reducing the fluctuation amount of the main injection in accordance with the rail pressure to overlay it on the reference fluctuation pattern is calculated.
• the change of K2 is shown in FIG. 10B.
• the value of K2 becomes 1.0.
• the rail pressure becomes lower than the reference rail pressure the value of K2 becomes larger than 1.0, while when the rail pressure becomes higher than the reference rail pressure, the value of K2 becomes smaller than 1.0.
• the contraction rate or expansion rate K3 of the fluctuation pattern when contracting or expanding the fluctuation pattern of the main injection amount in a direction increasing or reducing the fluctuation amount of the main injection in accordance with the main injection amount QM to overlay it on the reference fluctuation pattern is calculated.
• This change of K3 is shown in FIG. IOC.
• FIG. 10C near the main injection amount serving as the reference, the value of K3 becomes 1.0.
• the main injection amount becomes lower than the reference main injection amount
• the value of K3 becomes larger than 1.0
• the value of K3 becomes smaller than 1.0.
• the contraction rate or expansion rate K4 of the fluctuation pattern when contracting or expanding the fluctuation pattern of the main injection amount in a direction increasing or reducing the fluctuation amount of the main injection in accordance with the pilot injection amount to overlay it on the reference fluctuation pattern is calculated.
• This change of K4 is shown in FIG. 10D.
• the value of K4 becomes 1.0.
• the value of K4 becomes larger than 1.0, while when the pilot injection amount becomes higher than the reference pilot injection amount, the value of K4 becomes smaller than 1.0.
• the reference fluctuation amount dQ calculated at step 108 is multiplied with the reciprocal of the contraction rates or expansion rates K2 , K3 , and K4 to calculate the final fluctuation amount dQ of the main injection.
• a command value of the main injection is corrected so that the actual injection amount becomes the target value based on this fluctuation amount dQ. For example, when the fluctuation amount dQ is plus, the command value of the main injection is corrected so that the main injection amount QM calculated at step 101 is reduced by the fluctuation amount dQ and the actual injection amount becomes the reduced main injection amount (QM-dQ).
• the command value of the main injection is corrected so that the main injection amount QM is increased by the fluctuation amount dQ and the actual injection amount becomes the increased main injection amount (QM+dQ). In this way, the actual injection amount is controlled to the target value QT.
• the processing for injection of the pilot injection and main injection is performed. Now, as explained above, the main injection amount fluctuates due to the pressure pulsation occurring in the nozzle chamber 34, but this main injection amount also fluctuates due to the fluctuation of the opening timing of the needle valve 31.
• the overflow control valve 40 opens, the fuel pressure in the pressure control chamber 36 gradually falls, and the needle valve 31 opens when the pressure difference between the needle chamber 34 and the pressure control chamber 36 becomes at least a fixed pressure.
• the pressure difference between the needle chamber 34 and the pressure control chamber 36 will become at least a fixed value.
• the opening timing of the needle valve 31 will be advanced.
• the pressure pulsation causes the fuel pressure in the nozzle chamber 34 to rapidly fall or the fuel pressure in the pressure control chamber 36 to rapidly rise, time will be required until the pressure difference between the needle chamber 34 and the pressure control chamber 36 becomes at least a fixed value, so the opening timing of the needle valve 31 is delayed.
• the opening timing of the needle valve 31 fluctuates in accordance with the rate of change of the pressure pulsation, that is, the differentiated value of the change of the pressure pulsation.
• the opening timing of the needle valve 31 if the opening timing of the needle valve 31 is advanced, the main injection amount will increase, while if the opening timing of the needle valve 31 is delayed, the main injection amount will decrease. Therefore, if the opening timing of the needle valve 31 fluctuates due to the effect of the rate of change of the pressure pulsation, the main injection amount will fluctuate along with this. In this way, the main injection amount fluctuates due to both the fluctuation of the injection amount due to fluctuation of the fuel pressure in the nozzle chamber 34 and fluctuation of the fluctuation amount due to fluctuation in the opening timing of the needle valve 31. However, the injection amount when the needle valve 31 opens is determined by the fuel pressure in the suck chamber 32. As shown in FIG.
• the fluctuation amount dQ of the main injection amount shown in FIG. 7 includes both the fluctuation amount of the injection amount due to pulsation in the nozzle chamber 34 and the fluctuation amount of the injection amount due to fluctuation of the opening timing of the needle valve 31.
• the main injection amount is small such as shown in FIG. 6, the lift of the needle valve 31 is small.
• the pressure pulsation occurring in the nozzle chamber 32 does not propagate much at all in the suck chamber 32. Therefore, when main injection amount is small, there is not that much fluctuation in the injection amount due to pressure pulsation of the nozzle chamber 34, that is, pressure pulsation in the suck chamber 32. At this time, the fluctuation of the main injection amount due to fluctuation of the opening timing of the needle valve 31 becomes dominant. However, the fluctuation in the main injection due to pressure pulsation in the nozzle chamber 32 is due to the magnitude of the absolute pressure in the nozzle chamber 32.
• the fluctuation in the opening timing of the needle valve 31 is not due to the magnitude of the absolute pressure in the nozzle chamber 34, but is due to the rate of change of the fuel pressure in the nozzle chamber 34 or pressure control chamber 36. Therefore, the fluctuation pattern of the fluctuation amount dQ of the main injection amount shown in FIGS. 6A to 6C where the fluctuation of the opening timing of the needle valve 31 dominates the fluctuation of the main injection amount and the fluctuation pattern of the fluctuation amount dQ of the main injection amount shown in FIGS. 7A to 7C where both the effect due to the pressure pulsation in the nozzle chamber 34 and the effect due to the fluctuation of the opening timing of the needle valve 31 appear differ somewhat. Therefore, when making the fluctuation patterns shown in FIGS.
• the fluctuation amount dQ of the main injection fluctuates by a fluctuation pattern as shown in FIG. 6A to FIG. 8B, but when the injection amount of the prior injection is large as shown by M of FIG. 3B, the fluctuation amount dQ of the later injection will fluctuate by a considerably different fluctuation pattern from the fluctuation pattern shown in FIG. 6A to FIG. 8C. Therefore, when there are cases where the injection amounts of the prior injection are small and large as shown in FIG.
• the map of the fluctuation amount dQ of the later injection standardized for when the injection amount of the prior injection is small and the injection amount of the later injection is small the map of the fluctuation amount dQ of the later injection standardized for when the injection amount of the prior injection is small and the injection amount of the later injection is large
• the map of the fluctuation amount dQ of the later injection standardized for when the injection amount of the prior injection is large and the injection amount of the later injection is large and, when finding the fluctuation amount dQ of the later injection, to selectively use one of these four maps in accordance with the injection amount of the prior injection and the injection amount of the later injection.
• FIGS. 11A to 11C show the relationship between the time interval Ti (msec) and the fluctuation amount ⁇ ( ⁇ msec) of the opening timing of the needle valve 31. Further, FIGS. 11A to lie show the case where the pilot injection amount is 2 (mm 3 ).
• the D marks show when the rail pressure is 48 MPa
• the o marks show when the rail pressure is 80 MPa
• the ⁇ marks show when the rail pressure is 128 MPa.
• FIG. 11A shows the actual value of the fluctuation amount ⁇ of the opening timing of the needle valve 31 at each rail pressure.
• FIG. 11A shows the actual value of the fluctuation amount ⁇ of the opening timing of the needle valve 31 at each rail pressure.
• FIG. 11B shows the case when making the rail pressure 80 MPa the reference rail pressure, making the fluctuation pattern of the opening timing of the needle valve 31 at this time the reference fluctuation pattern, and contracting or expanding the fluctuation pattern when the rail pressure is 48 MPa and 128 MPa shown in FIG. 11A in the time interval axis direction so that the period of upward and downward fluctuation of the fluctuation patterns match the period of upward and downward fluctuation of the reference fluctuation pattern.
• FIG. 11C shows the case when contracting or expanding the fluctuation patterns when the rail pressure is 48 MPa and 128 MPa shown in FIG. 11B in the vertical direction, that is, the direction increasing or decreasing the fluctuation amount ⁇ of the opening timing of the needle valve 31, so that these fluctuation patterns overlay the reference fluctuation pattern.
• FIGS. 12A and 12B show the relationship between the time interval Ti and the fluctuation amount dQt (mm 3 ) of the main injection due to the effects of only the fluctuation of the injection pressure obtained by subtracting from the actual fluctuation amount dQ (mm 3 ) of the main injection the fluctuation amount dQm of the main injection due to fluctuation of the opening timing of the needle valve 31. Further, FIGS. 12A and 12B show the case where the pilot injection amount is 2 (mm 3 ) and the rail pressure is the reference rail pressure 80 MPa.
• FIG. 12A shows the fluctuation amount dQt of the main injection at each main injection amount when the rail pressure is the reference rail pressure 80 MPa.
• FIG. 12B shows the case of making the fluctuation pattern when the rail pressure is the standard rail pressure 80 MPa and the main injection amount is 20 (mm 3 ) the reference fluctuation pattern and contracting or expanding the fluctuation patterns at the time of the main injection amounts of 5 (mm 3 ), 10 (mm 3 ), 30 (mm 3 ), and 40 (mm 3 ) in the vertical direction, that is, the direction increasing or decreasing the fluctuation amount dQt of the main injection, so that the fluctuation patterns overlay the reference fluctuation pattern. If taking out the fluctuation amount dQt of the main injection due to just fluctuation of the injection pressure, it is possible to standardize the fluctuation pattern as shown in FIG. 12B. Note that in FIG.
• the first fuel injection control method is the method of finding the fluctuation amount ⁇ of the opening timing of the needle valve 31 from FIG.
• FIG. 13 and FIG. 14 shows a fuel injection control routine for executing the first fuel injection control method. Referring to FIG. 13 and FIG. 14, first, at step 200, the total injection amount QT is calculated from the map shown in FIG. 4A.
• the main injection amount QM is calculated from the map shown in FIG. 4B.
• the total injection amount QT is subtracted by the main injection amount QM to calculate " the pilot injection amount QP.
• the main injection start timing ⁇ M is calculated from the map shown in FIG. 5A.
• the time interval TI is calculated from the map shown in FIG. 5B.
• the pilot injection start timing ⁇ P is calculated from the main injection start timing ⁇ M and the time interval TI .
• the contraction rate or expansion rate IK1 when contracting or expanding the fluctuation pattern of the fluctuation amount ⁇ of the opening timing of the needle valve 21 in a direction increasing or reducing the time interval in accordance with the rail pressure to overlay it on the reference fluctuation pattern is calculated.
• This contraction rate or expansion rate IK1 is shown in FIG. 15A. If the reference rail pressure is 80 MPa, when the rail pressure is near 80 MPa, the contraction rate or expansion rate IKl is 1.0. As the rail pressure becomes lower than the reference rail pressure, IKl decreases, that is, the fluctuation pattern contracts, while as the rail pressure becomes higher than the reference rail pressure, IKl increases, that is, the fluctuation pattern is expanded.
• the contraction rate or expansion rate IKl of the fluctuation pattern is multiplied with the time interval TI so as to calculate the modified time interval Ti.
• the reference rail pressure is made 80 MPa and the reference pilot injection amount QP is made 20 (mm 3 ), that is, if the fluctuation amount ⁇ of the opening timing shown by the o marks in FIG. 11B is made the reference fluctuation amount, the reference fluctuation amount of the opening timing in accordance with the modified time interval Ti is calculated.
• the contraction rate or expansion rate IK2 of the fluctuation pattern when contracting or expanding the fluctuation pattern of the opening timing in a direction increasing or reducing the fluctuation amount of the opening timing in accordance with the rail pressure to overlay it on the reference fluctuation pattern is calculated.
• the change of IK2 is shown in FIG. 15B.
• the value of IK2 becomes 1.0.
• the rail pressure becomes lower than the reference rail pressure the value of IK2 becomes larger than 1.0
• the rail pressure becomes higher than the reference rail pressure the value of IK2 becomes smaller than 1.0.
• the contraction rate or expansion rate IK3 of the fluctuation pattern when contracting or expanding the fluctuation pattern of the opening timing in a direction increasing or reducing the fluctuation amount of the opening timing in accordance with the pilot injection amount to overlay it on the reference pattern is calculated.
• This change of IK3 is shown in FIG. 15C.
• the value of IK3 becomes 1.0.
• the pilot injection amount becomes lower than the reference pilot injection amount
• the value of IK3 becomes larger than 1.0
• the pilot injection amount becomes higher than the reference pilot injection amount the value of IK3 becomes smaller than 1.0.
• the reference fluctuation amount ⁇ of the opening timing calculated at step 208 is multiplied with the reciprocal of the contraction rates or expansion rates IK2 and IK3 to calculate the final fluctuation amount ⁇ of the opening timing.
• a command value of the opening timing is corrected so that the actual opening timing becomes the target value based on this fluctuation amount ⁇ . For example, when the opening timing is plus, the command value of the main injection is corrected so that the main injection start timing ⁇ M calculated at step 203 is delayed by exactly the fluctuation amount ⁇ . On the other hand, if the opening timing is minus, the command value of the opening timing is corrected so that the main injection start timing ⁇ M calculated at step 203 is advanced by exactly the fluctuation amount ⁇ .
• the contraction rate or expansion rate FK1 when contracting or expanding the fluctuation pattern of the fluctuation amount dQ of the main injection in a direction increasing or reducing the time interval in accordance with the rail pressure to overlay it on the reference fluctuation pattern is calculated.
• This contraction rate or expansion rate FKl is shown in FIG. 16A. If the reference rail pressure is 80 MPa, when the rail pressure is near 80 MPa, the contraction rate or expansion rate FKl is 1.0.
• the contraction rate or expansion rate FKl of the fluctuation pattern is multiplied with the time interval TI to calculate the modified time interval Ti.
• the reference rail pressure is made 80 MPa
• the main injection amount QM serving as a reference is made 20 (mm 3 )
• the pilot injection amount QP serving as a reference is made 2 (mm 3 ), that is, when the fluctuation amount shown by the ⁇ marks in FIG.
• the contraction rate or expansion rate FK2 of the fluctuation pattern when contracting or expanding the fluctuation pattern of the main injection amount in a direction increasing or reducing the fluctuation amount of the main injection in accordance with the rail pressure to overlay it on the reference fluctuation pattern is calculated.
• This change of FK2 is shown in FIG. 16B.
• the value of FK2 becomes 1.0.
• the rail pressure becomes lower than the reference rail pressure the value of FK2 becomes larger than 1.0
• the rail pressure becomes higher than the reference rail pressure the value of FK2 becomes smaller than 1.0.
• the contraction rate or expansion rate FK3 of the fluctuation pattern when contracting or expanding the fluctuation pattern of the main injection amount in a direction increasing or reducing the fluctuation amount of the main injection in accordance with the main injection amount QM to overlay it on the reference fluctuation pattern is calculated.
• This change of FK3 is shown in FIG. 16C.
• the value of FK3 becomes 1.0.
• the value of FK3 becomes larger than 1.0, while when the main injection amount becomes higher than the reference main injection amount, the value of FK3 becomes smaller than 1.0.
• the contraction rate or expansion rate FK4 of the fluctuation pattern when contracting or expanding the fluctuation pattern of the main injection amount in a direction increasing or reducing the fluctuation amount of the main injection in accordance with the pilot injection amount to overlay it on the reference fluctuation pattern is calculated.
• This change of FK4 is shown in FIG. 16D.
• the value of FK4 becomes 1.0.
• the pilot injection amount becomes lower than the reference pilot injection amount the value of FK4 becomes larger than 1.0
• the pilot injection amount becomes higher than the reference pilot injection amount the value of FK4 becomes smaller than 1.0.
• the reference fluctuation amount dQ calculated at step 215 is multiplied with the reciprocal of the contraction rates or expansion rates FK2, FK3, and FK4 to calculate the final fluctuation amount ⁇ of the main injection.
• a command value of the main injection is corrected so that the actual injection amount becomes the target value based on this fluctuation amount dQ. For example, when the fluctuation amount dQ is plus, the command value of the main injection is corrected so that the main injection amount QM calculated at step 201 is reduced by the fluctuation amount dQ and the actual injection amount becomes the reduced main injection amount (QM-dQ).
• FIG. 17 and FIG. 18 show a fuel injection control routine for executing the second fuel injection control method. In this routine, the only difference from the routine shown in FIG. 13 and FIG. 14 is step 212' and 220'.
• steps 200 to 211, 213 to 219, and 221 are the same as steps 200 to 211, 213 to 219, and 221 in FIG. 13 and FIG. 14. Therefore, below, only steps 212' and 220' in the routine shown in FIG. 17 and FIG. 18 will be explained.
• the fluctuation amount ⁇ Qm for when the opening timing of the needle valve 31 fluctuates by a unit time is found in advance by experiments.
• the main injection command value is corrected based on the fluctuation amount dQm of the main injection and the fluctuation amount dQ of the main injection found at step 219.
• the main injection command value is corrected by any of these methods.
• the simplest method is to add to the main injection amount QM calculated at step 201 the fluctuation amounts dQ and dQm and make the added up main injection amount (QM+dQ+dQm) the final main injection amount.
• the injection start timing is left as it is, while the injection end timing is determined so that the actual main injection amount becomes the final main injection amount (QM+dQ+dQm) .

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)

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